Add video card insert feature + MkDocs video hydration + fixes

- New video card block for GrapesJS landing pages, email templates,
  MkDocs export, and documentation editor Insert dropdown
- Shared HTML generators in admin/src/utils/videoCardHtml.ts
- MkDocs video-player.js hydrates .video-card-block elements:
  thumbnail fix via MEDIA_API_URL, click-to-play inline, Gallery link
- Media API CORS: auto-add MkDocs + docs subdomain origins
- env_config_hook.py: smart Docker hostname detection, ADMIN_PORT
  resolution, pass env vars to MkDocs container
- Gallery URL uses /gallery?expanded=ID format
- VideoPickerModal: fix double /api prefix and Docker hostname thumbs
- Seed: default-video-card PageBlock
- Remove V1 legacy code (influence/, map/)

Bunker Admin

mkdocs/docs/assets/css/video-player.css

@@ -102,14 +102,20 @@
 /* Responsive video containers */
 @media (max-width: 768px) {
   .video-block,
-  .advanced-video-container {
+  .advanced-video-container,
+  .video-card-block {
     margin: 1.5rem auto;
   }
 
   .video-block video,
-  .advanced-video-container video {
+  .advanced-video-container video,
+  .video-card-player video {
     border-radius: 4px;
   }
+
+  .video-card-block {
+    max-width: 100%;
+  }
 }
 
 /* Video placeholder (shown during GrapesJS export before hydration) */
@@ -138,9 +144,45 @@
   margin: 0;
 }
 
+/* Video card block (YouTube-style preview card) */
+.video-card-block {
+  margin: 2rem auto;
+  max-width: 480px;
+  cursor: pointer;
+  transition: transform 0.15s ease, box-shadow 0.15s ease;
+}
+
+.video-card-block:hover {
+  transform: translateY(-2px);
+}
+
+.video-card-block a {
+  text-decoration: none !important;
+  color: inherit !important;
+}
+
+/* Video card gallery button */
+.video-card-gallery-btn:active {
+  transform: scale(0.96);
+}
+
+/* Video card inline player (after clicking thumbnail) */
+.video-card-player video {
+  width: 100%;
+  display: block;
+  background: #000;
+}
+
+.video-card-player video:focus {
+  outline: 2px solid var(--md-primary-fg-color);
+  outline-offset: 2px;
+}
+
+
 /* Ensure videos respect content width in Material theme */
 .md-content .video-block,
-.md-content .advanced-video-container {
+.md-content .advanced-video-container,
+.md-content .video-card-block {
   max-width: 100%;
 }